Hybrid signal router

FIELD

p-0002The embodiments disclosed herein relate to systems and methods for switching and routing signals including video signals and audio/video signals.

BACKGROUND

p-0003In recent years, the availability of high quality video signals, including audio/video signals, has increased substantially. At the same time, the number of sources of video signals has increased rapidly. Modern video production and processing facilities, such as television stations and cable and satellite broadcasters must frequently use and process a large number of high bandwidth signals simultaneously. The video signal processing systems in such facilities must be able to receive, store and provide large numbers of such signals. There exists a need for video signal switching and routing systems and methods capable of handling large numbers of video signals including video signals having a high bandwidth.

SUMMARY

p-0004In one aspect, the disclosed embodiments provide a signal routing system comprising: a plurality of input ports for receiving a plurality of input signals; a plurality of output ports for transmitting a plurality of output signals; a crosspoint switch for coupling each of the input ports to one or more of the output ports to allow each input signal to be coupled to one or more output ports; an aggregation module for combining a plurality of input signals into a one or more compressed signals, wherein each of the compressed signals corresponds to two or more of the input signals; and an optical aggregation module for combining a plurality of the compressed signals into an optical signals corresponding to a plurality of the inputs signals, wherein the optical aggregation module is coupled to a communication network.

p-0005In some embodiments, the system includes an optical deaggregation module coupled to the communication network for receiving an optical signal and deaggregating a plurality of compressed signals from the optical signal and a deaggregation module for deaggregating the compressed signals to form video signals corresponding to the received optical signal, wherein the deaggregation module is coupled to the crosspoint switch to provide the video signals to the crosspoint switch, wherein the crosspoint switch may be configured to couple the video signals to one or more of the output ports.

p-0006In some embodiments, the system includes a controller coupled to the crosspoint switch to coordinate the operation of the crosspoint switch with other components of the system.

p-0007In some embodiments, at least some of the input signals are electrical signals and wherein the crosspoint switch is configured to switch electrical domain signals between the input ports and output ports.

p-0008In some embodiments, at least some of the input signals are optical signals and wherein the crosspoint switch is configured to switch electrical domain signals between the input ports and output ports.

p-0009In some embodiments, the aggregation module includes one or more signal compression modules.

p-0010In some embodiments, the aggregation module includes one or more signal multiplexing modules.

p-0011In another aspect, the described embodiments provide signal routing system comprising: a plurality of input cards for receiving a plurality of input signals; a plurality of output cards for transmitting a plurality of output signals; a crosspoint switch coupled to the input cards and to the output cards for receiving at least some of the input signals and for switching at least some of the input signals to one or more of the output cards; and a packet switched router coupled to the input cards for receiving one or more optical signals, each of the optical signals corresponding to one or more of the input signals.

p-0012In some embodiments, at least some of the input cards include: one or more input ports for receiving a plurality of electrical domain input signals; an aggregation module for combining a plurality of input signals into a one or more of the compressed signals; and an optical aggregation module for combining a plurality of the compressed signals into an optical signals corresponding to a plurality of the inputs signals, wherein the optical aggregation module is coupled to the packet switched router.

p-0013In some embodiments, at least some of the input cards include: one or more input ports for receiving one or more optical domain input signals.

p-0014In some embodiments, the system includes one or more signal extraction modules, wherein at least some of the signal extraction modules are coupled between one of the input cards and the packet switched router to receive optical signals and to provide packetized signals corresponding to one or more input signals to the packet switched router.

p-0015In some embodiments, the system includes one or more signal transmission modules for retrieving packetized signals from the packet switched router and for providing one or more compressed optical signals corresponding to the retrieved packetized signals.

p-0016In some embodiments, at least some of the signal transmission modules is coupled to one of the output cards to provide one or more compressed optical signals to the coupled output card.

p-0017In some embodiments, the coupled output cards include an optical deaggregation module and an electrical deaggregation module for providing one of more output signals corresponding to a packetized signal included in a compressed optical signal.

p-0018In some embodiments, the system includes a controller coupled to the crosspoint switch to coordinate the operation of the crosspoint switch with other components of the system.

p-0019In some embodiments, the system includes a controller coupled to the packet switched router to coordinate the operation of the packet switched router with other components of the system.

p-0020In another aspect, the described embodiments provide a method of routing signals, the method comprising: receiving a plurality of input signals at a plurality of input ports; coupling at least some of the signals to a crosspoint switch, wherein the crosspoint switch is coupled to a plurality of output ports; within the crosspoint switch, coupling at least some of the input ports to one or more of the output ports thereby transporting at least some of the input signals to such output ports; generating one or more optical signals, wherein each of the optical signals corresponds to one or more of the input signals; and providing the optical signals to a communication network.

p-0021In some embodiments, the system includes generating the optical signals by aggregating one or more of the input signals.

p-0022In some embodiments, the method includes generating the optical signals by aggregating one or more of the input signals in the electrical domain and in the optical domain.

p-0023In some embodiments, the method includes aggregating the input signals by compressing the input signals.

p-0024In some embodiments, the method includes aggregating the input signals by multiplexing the input signals.

p-0025In some embodiments, the method includes receiving optical signals from the communication network and deaggregating the received optical signals to extract one or more signals encoded in the received optical signals.

p-0026In some embodiments, the method includes coupling the extracted signals to the output ports.

p-0027In another aspect, the described embodiments provide a method of routing signals, the method comprising: receiving a plurality of input signals at a plurality of input ports; coupling at least some of the signals to a crosspoint switch, wherein the crosspoint switch is coupled to a plurality of output ports; within the crosspoint switch, coupling at least some of the input ports to one or more of the output ports thereby transporting at least some of the input signals to such output ports; generating one or more optical signals, wherein each of the optical signals corresponds to one or more of the input signals; and providing the optical signals to a packet switched router.

p-0028In some embodiments, the method includes extracting one or more input signals from the one or more optical signals; converting each of the extracted input signals into a packetized signal; and storing each of the packetized signals in a memory module of the packet switched router.

p-0029In some embodiments, the method includes retrieving one or more packetized streams from the memory module; and generating one or more compressed optical signals corresponding to the retrieved packetized streams.

p-0030In some embodiments, the method includes deaggregating at least some of the compressed optical signals to form one or more output signals and providing the output signals at one or more of the output ports.

p-0031In some embodiments, at least some of the input signals are electrical domain signals.

p-0032In some embodiments, the method includes at least some of the input signal are optical domain signals.

p-0033These and other aspects are described further below.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0034Several example embodiments are described below with reference to the drawings, in which:

p-0035<figref idrefs="DRAWINGS">FIG. 1</figref> illustrates a first signal routing system;

p-0036<figref idrefs="DRAWINGS">FIG. 2</figref> illustrates an aggregation module of the system of <figref idrefs="DRAWINGS">FIG. 1</figref>;

p-0037<figref idrefs="DRAWINGS">FIG. 3</figref> illustrates another signal routing system;

p-0038<figref idrefs="DRAWINGS">FIG. 4</figref> illustrates yet another signal routing system; and

p-0039<figref idrefs="DRAWINGS">FIG. 5</figref> illustrates a packetized signal of the system of <figref idrefs="DRAWINGS">FIG. 4</figref>.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

p-0040It will be appreciated that numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Furthermore, this description is not to be considered as limiting the scope of the embodiments described herein in any way, but rather as merely describing implementation of the various embodiments described herein.

p-0041The embodiments of some of the methods, systems and apparatus described herein may be implemented in hardware or software, or a combination of both. These embodiments may be implemented in computer programs executing on programmable computers, each computer including at least one processor, a data storage system (including volatile memory or non-volatile memory or other data storage elements or a combination thereof), and at least one communication interface. Program code is applied to data to perform the functions described herein and to generate output information. The output information is applied to one or more output devices, in known fashion. In some embodiments, the communication interface may be a network communication interface. In embodiments in which elements of the invention are combined, the communication interface may be a software communication interface, such as those for inter-process communication (IPC). In still other embodiments, there may be a combination of communication interfaces implemented as hardware, software, and combination thereof.

p-0042Each program may be implemented in a high level procedural or object oriented programming or scripting language, or both, to communicate with a computer system. For example, a program may be written in XML, HTML 5, and so on. However, alternatively the programs may be implemented in assembly or machine language, if desired. The language may be a compiled or interpreted language. Each such computer program may be stored on a storage media or a device (e.g. ROM, magnetic disk, optical disc), readable by a general or special purpose programmable computer, for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the system may also be considered to be implemented as a non-transitory computer-readable storage medium, configured with a computer program, where the storage medium so configured causes a computer to operate in a specific and predefined manner to perform the functions described herein.

p-0043Furthermore, the methods, systems and apparatus of the described embodiments are capable of being distributed in a computer program product including a physical non-transitory computer readable medium that bears computer usable instructions for one or more processors. The medium may be provided in various forms, including one or more diskettes, compact disks, tapes, chips, magnetic and electronic storage media, and the like. The computer useable instructions may also be in various forms, including compiled and non-compiled code.

p-0044Reference is first made to <figref idrefs="DRAWINGS">FIG. 1</figref>, which illustrates a signal routing system <b>100</b>. System <b>100</b> includes an electrical-domain signal router <b>102</b>, an optical signal aggregation module <b>104</b>, an optical signal deaggregation module <b>106</b>, a communication network <b>108</b> and a controller <b>110</b>. Controller <b>110</b> is coupled to the router <b>102</b>, aggregation module <b>104</b> and deaggregation module <b>106</b> to coordinate and control their respective and collective operations.

p-0045Router <b>102</b> has a plurality of input ports <b>116</b>, a plurality of output ports <b>118</b> and includes a switching fabric <b>120</b> and an electrical domain signal aggregation module <b>124</b>.

p-0046The switching fabric <b>120</b>, which can also be referred to as a crosspoint or a crosspoint switch, can be configured to couple an input signal <b>117</b> received at any of the input ports <b>116</b> to any of the output ports <b>118</b> as an output signal <b>119</b>. Router <b>102</b> is coupled to and receives control signals from controller <b>110</b>. Router <b>102</b> is responsive to the control signals to configure the switching fabric <b>120</b> to achieve a desired coupling between the input ports <b>116</b> and the output ports <b>118</b>. In some embodiments, router <b>102</b> may include input processing elements that process input signals <b>117</b> to generate versions of the input signals that are then provided to the switching fabric <b>120</b>. In some embodiments, router <b>102</b> may include output processing elements that process signals received from the switching fabric to generate versions of the input signals <b>117</b> which are then provided at the output ports as output signals <b>119</b>. The switching fabric <b>120</b> may be a physical switching structure that electrically couples input ports <b>116</b> to one or more output ports <b>118</b> or it may be a logical switching structure that utilizes buffers, such as first in-first out buffers, to store input signals (or versions of input signals). The buffered signals are then recalled from the buffers and provided (in their buffered form or in a version of the buffered form) as output signals <b>119</b>. The switching fabric effectively provides a point-to-point coupling between an input port <b>116</b> and one or more output ports <b>118</b>.

p-0047The number of input ports <b>116</b> and output ports <b>118</b> provided in a router can vary and can be expressed in the form Number of Input Ports×Number of Output Ports. This can be referred to as the size of a router. For example, a router having 576 input ports and 576 output ports can be said to have a size of 576×576. Routers can have various sizes, including systems smaller than 576×576 and others that are larger. Routers used to switch media signals such as video signals and video transport streams may be used to switch a variety of different signals types that have different bit rates and bandwidth requirements for the transmission and switching devices through which the signals pass. For example, some standard definition video signals may have a bit rate of 143 Mbit/s or 270 Mbit/s (SD-SDI), while high definition video signals may have a bit rate of 1.485 Gbit/s (HD-SDI). Other signals may have a higher bit rate of 2.970 Gbit/s (3G-SDI). These signals types are only examples of the many different SDI (serial digital interface) signals standards issued by the Society of Motion Picture and Television Engineers (SMPTE). Other groups have issued various other standards for video signals and video routers may be typically be capable of transporting and switching some or all of these many different signal types.

p-0048Reference is made to <figref idrefs="DRAWINGS">FIG. 2</figref>, which illustrates aggregation module <b>124</b> in greater detail. Aggregation module <b>124</b> includes a time-division-multiplexing (TDM) module <b>126</b>, a mathematically lossless compression module <b>128</b> and a visually lossless compression module <b>130</b>. Each of the input signals <b>117</b> received at an input port <b>116</b> is also coupled to aggregation module <b>124</b>.

p-0049Groups of inputs signals <b>117</b> are combined into a TDM signal <b>132</b> in which the signals in each group are time division multiplexed. For example, the input signals <b>117</b> may be grouped into groups of two or more signals, which may then be time division multiplexed into a single TDM signal <b>132</b>. By combining multiple input signals <b>117</b> into a set of TDM signals, the number of individual signals that must be transported can be reduced. The number of input signals <b>117</b> that can be combined into a single TDM signal <b>132</b> will typically depend on the bitrate of the input signals and bandwidth of the transmission line or cable <b>134</b> used to transport the TDM signals. For example, three input signals <b>117</b><i>a</i>-<i>c </i>in a 3G-SDI format (having a bitrate of 2.970 GBit/s) may be time division multiplexed in a single TDM signal transported on a 10 GB/s transmission line <b>134</b><i>a </i>(which is often referred to as a 10 GigE transmission line). The input signals <b>117</b> combined in a TDM signal may have different bitrates. Larger groups of input signals that have a smaller total bitrate may be combined in a TDM signal that can be transmitted on a particular transmission line.

p-0050Typically, the input signals <b>117</b> will be combined into a plurality of TDM signals <b>132</b> by the TDM module <b>126</b>. For example, 576 3G-SDI signals can be combined into 192 TDM signals that can be transported on 192 10 GB/s transmission lines. The TDM module <b>126</b> will typically include two or more TDM components to handle the total number of input signals <b>117</b> on real time so that a plurality of TDM signals <b>132</b> may be assembled simultaneously.

p-0051The TDM signals <b>132</b> are then coupled to mathematically lossless compression module <b>128</b>, which compresses the signals to reduce the bandwidth required to transmit the signals. Mathematically lossless compression module <b>128</b> extracts each video signal <b>117</b> from its TDM signal <b>132</b> and applies a compression algorithm to the video signal to produce a corresponding lossless compressed signal <b>136</b>, which has a reduced amount of data compared to the original video signal <b>117</b>. The compression algorithm applied is mathematically lossless such that the original video signal <b>117</b> may be recreated by applying a mathematical decompression algorithm to the corresponding lossless compressed signal <b>136</b>. The mathematically lossless compression of the video signals reduces their total bitrate and allows a larger number of signals to be combined a single transmission line of a given bandwidth. For example, if mathematically lossless compression module <b>128</b> can compress the input signals <b>117</b> into lossless compressed signals <b>136</b> having half the bitrate of the original input signals, then twice as many inputs signals may be combined in a TDM signal on a given transmission line. In this example, up to six 3G-SDI signals could be combined on a single 10 GB/s transmission line. The mathematically lossless compression module <b>128</b> combines the lossless compress signals <b>136</b> into a set of lossless compressed TDM signals <b>138</b>, each of which will typically contain more individual signals corresponding the original input signals <b>117</b> that the TDM signals <b>132</b>. The lossless compressed TDM signals <b>138</b> are transmitted on transmission lines <b>140</b>. Typically, the visually lossless compression module <b>130</b> may contain a plurality of lossless compression components to simultaneously compress the input signals <b>117</b> and to produce the In the example give above of 576 3G-DSI signals that could be combined into 192 TDM signals <b>132</b>, if these signals can be compressed on a 2:1 compression ratio by the mathematically lossless compression module <b>128</b>, then they can be combined into 96 lossless compressed TDM signals <b>138</b> transmitted on 96 10 GB/s transmission lines <b>140</b>.

p-0052The lossless compressed TDM signals <b>138</b> are then coupled to visually lossless compression module <b>130</b>. Visually lossless compression module <b>130</b> extracts the lossless compressed signals applies a further compression on the lossless compressed signals <b>136</b> to produce a visually compressed signal <b>144</b> for each lossless compressed signal <b>136</b>. Visually lossless compression module <b>130</b> applies a visually lossless compression by removing components of an original video signal <b>117</b> that would not normally be observed (or would only be marginally observed) by viewers of a reproduction of the video signal. Various visually lossless compression algorithms may be used to compress different types of video signals or to achieve different degrees of compression. For example, visually lossless compression algorithms such as color space reduction, chroma subsampling, transform coding or fractal compression may be applied to reduce the size of a video signal without affecting the quality of the reproduced signal when viewed. These lossy compression algorithms will typically produce a compressed video signal that cannot be decompressed to produce a signal identical to the original video signal. However, by selecting parameters of the compression algorithm the degree of compression and any visual effect of compression may be limited or effectively eliminated. A skilled person will be able to select a compression algorithm and parameters to achieve a desired balance between compression and video signal quality.

p-0053In some embodiments, a visually lossy compressed signal may be acceptable, and the compression module <b>130</b> may implement a visually lossy compression algorithm.

p-0054The visually compressed signals <b>144</b> corresponding to the original input signal <b>117</b> are time multiplexed into TDM visually compressed signals <b>146</b>. The number of visually compressed signals <b>144</b> that may be combined into a single TD visually compressed signal <b>146</b> that can be transported on a particular Depending on the degree of compression provided by the visually lossless compression module <b>130</b>, a greater number of visually compressed signals <b>144</b> may be combined in a single TD visually compressed signal <b>146</b> that can be carried on a particular transmission line than the number of lossless compressed signals <b>136</b> combined in a lossless compressed TDM signal <b>138</b> transmitted on the same transmission line. For example, if a 3G-SDI signal that has already been compressed to form a lossless compressed signal <b>136</b> can further be compressed to provide a visually compressed signal that has a third of the bitrate of the lossless compressed signal, then eighteen such visually compressed signals can be combined into a single TDM visually compressed signal <b>146</b> that can be transmitted on a 10 GB/s transmission line. In situations where visually compressed version of smaller signals (such as HD-SDI, SD-SDI and other signals have a lower bit rate than a 3G-SDI signal) are included in a TDM visually compressed signal <b>146</b>, then a larger number of such signals could be combined in a TDM visually compressed signal that can be transmitted on a single 10 GB/s transmission line.

p-0055In various embodiments, input signals may be compressed and multiplexed using various formats and combinations of techniques to provide compressed signals <b>146</b> in various manners, depending on the characteristics of the input signals, the communication links between the components of system <b>100</b> and the desired bandwidth for the compressed signals <b>146</b> and any intermediate signals used to form the compressed signals <b>146</b>.

p-0056If a router <b>102</b> (<figref idrefs="DRAWINGS">FIG. 1</figref>) receives 576 3G-SDI input signals <b>117</b>, the processing the input signals <b>117</b> through aggregation module <b>124</b> will result of 192 TDM signals <b>132</b>, 96 lossless compressed signals <b>136</b> and 32 TDM visually compressed signals <b>146</b>. If some or all of the inputs signals <b>117</b> have a bit rate lower than a 3G-SDI signal then visually lossless compressed versions of the signals could be combined into fewer than 32 TDM visually compressed signals <b>146</b>.

p-0057Referring again to <figref idrefs="DRAWINGS">FIG. 1</figref>, router <b>102</b> provides the TDM visually compressed signals <b>146</b> at a plurality of compressed signal output ports <b>150</b>. The TDM visually compressed signals are coupled to optical signal aggregation module <b>104</b>. Optical signal aggregation module <b>104</b> converts the TDM visually compressed signals <b>146</b> into corresponding compressed optical signals <b>152</b>. The optical signals <b>152</b> are then transmitted using wavelength division multiplexing (WDM) to transmits the optical signals <b>152</b> in groups on one or more optical fibers <b>154</b>. The number of optical fibers <b>154</b> required to carry on the optical signals <b>152</b> will depend on the number of optical signals <b>152</b>, and the WDM protocol applied. For example, if the optical aggregation module utilizes a coarse WDM (CWDM) protocol, then 32 optical signals <b>152</b> may typically be grouped into two groups of 16 signals and transmitted on two optical fibers. If the optical aggregation module utilizes a dense WDM (DWDM) protocol, it may be possible to transmit 32 or more optical signals <b>152</b> on a single optical fiber <b>154</b>.

p-0058The optical signals <b>152</b> are transported on fibers <b>154</b> to communication network <b>108</b>, which receives the optical signals <b>152</b> and can provide the optical signals to other devices coupled to communication network <b>108</b>. In some embodiments, communication network <b>108</b> may be capable to transmitting both optical and electrical signals. In some embodiments, the communication network may also include a wavelength division de-multiplexer <b>158</b> that can extract individual compressed optical signals <b>152</b> from the optical fiber <b>154</b>. The extracted compressed optical signals <b>152</b> may be transmitted through network <b>108</b> to devices coupled to the network.

p-0059Router <b>102</b> may also receive optical signals from the network <b>108</b>. To receive signal optical signals from the network <b>108</b>, router <b>102</b> is coupled to network <b>108</b> through an optical signal deaggregation module <b>106</b>. Optical deaggregation module <b>106</b> provides the opposite operation of aggregation module <b>104</b>. Optical deaggregation module <b>106</b> receives optical signals <b>162</b> from network <b>108</b> across one or more optical fibers <b>160</b>. The signals may be received in a WDM format or they may not be transmitted with other optical signals. The optical deaggregation module <b>106</b> converts the received optical signals <b>162</b> into corresponding compressed signals <b>164</b>. The compressed signals <b>146</b> are provided to an electrical domain deaggregation module <b>125</b> within router <b>102</b>.

p-0060Deaggregation module <b>125</b> deaggregates the compressed signals <b>164</b> to produce individual video signals. If the content of the compresses signals <b>164</b> is similar to the TDM visually compressed signals <b>146</b> described above, then deaggregation module <b>125</b> may include a visually lossless decompression module, a mathematically lossless decompression module and a time division demultiplexing module which are applied to reverse the operations described above in relation to aggregation module <b>124</b>. The deaggregation module <b>125</b> decompresses and demultiplexes the compressed signals <b>164</b> to produce individual video signals <b>166</b>. The video signals <b>166</b> may be coupled to the switching fabric <b>120</b>, through which they may be coupled to output ports <b>118</b> that are coupled to the switching fabric. The video signals may also be coupled to output ports <b>118</b> without be switched through the switching fabric.

p-0061Deaggregation module <b>125</b> may include various components to decompress, demultiplex and otherwise extract video signals <b>166</b> from the compressed signals <b>164</b>. In some embodiments, the compressed signals <b>164</b> may be in one or more particular format and the deaggregation module <b>125</b> is adapted to process the particular formats to provide the video signals <b>166</b>. In other embodiments, the compressed signals <b>164</b> may be received in various formats according to various compression and multiplexing standards. Some signals received by the deaggregation module may not be compressed or may not be multiplexed. In such embodiments, the deaggregation module contains decompression and demultiplexing components to process such signals to provide the video signals <b>166</b>.

p-0062In some embodiments, the electrical aggregation module <b>124</b> may similarly include various multiplexing and compression modules to provide signals to the optical aggregation module <b>104</b> in various formats as required for other devices coupled to the network <b>108</b>.

p-0063Reference is next made to <figref idrefs="DRAWINGS">FIG. 3</figref>, which illustrates a system <b>300</b>. Components of system <b>300</b> that are similar to components of system <b>100</b> are identified by similar reference numerals. System <b>300</b> includes several routers <b>302</b> that are coupled to network <b>308</b> through aggregation module <b>324</b> and deaggregation module <b>325</b>, in the manner described above in relation to router <b>102</b>, aggregation module <b>124</b>, deaggregation module <b>125</b> and network <b>108</b>.

p-0064Network <b>308</b> may have various devices and systems coupled to it. For example, in this embodiment, a digital video server <b>370</b> is coupled to the communication network <b>308</b>. Digital video server <b>370</b> includes a data storage element <b>372</b> in which the signals may be recorded for later retrieval and transmission to other devices.

p-0065Compressed optical signals <b>352</b> provided by aggregation modules <b>324</b> may be transmitted to the digital video server <b>370</b>. Within the digital video server <b>370</b>, the compressed optical signals are processed to extract versions of the video signals encoded in the compressed optical signal. The versions of the video signals are stored in the storage element <b>372</b>. The stored versions may be visually lossless compressed versions, mathematically compressed versions or decompressed versions of the original video signals. The versions are generated by suitable decompressing and demultiplexing components in the digital video server.

p-0066The versions of video signals may be transmitted across network <b>308</b> to routers <b>302</b> or to other devices coupled to the network <b>308</b>.

p-0067A wide variety of devices may be coupled to the network <b>308</b>. For example, a viewer system <b>374</b> may be coupled to network <b>308</b>. Viewer system <b>374</b> receives versions of video signals from digital video server <b>370</b>. The viewer system <b>374</b> includes a processing module <b>376</b> a viewer module <b>378</b>. The processing module <b>376</b> includes processing elements to convert the received versions of the video signals into displayable video signals. Such processing elements may include decompressors and demultiplexers. In addition, the processing elements may include rescalers and format converters to provide video signals in a format suitable for display at the viewer module <b>378</b>.

p-0068In some embodiments, the viewer module <b>378</b> may be a simple display screen that receives a single video signal from the processing module <b>376</b> and displays the video signal. In other embodiments, the viewer module <b>378</b> may be a multi-image display system that receives multiple video signals and displays them on one or more display screens. The viewer module <b>378</b> may receive video signals in one or more formats. For example, the processing module <b>376</b> may provide some or all of the video signals in a standardized format such as a common interchange format, which is then processed and displayed by the viewer module <b>378</b>.

p-0069System <b>100</b> and the variations described are only examples of the present invention. Many variations are possible. For example, other systems may implements a different combination of multiplexors or compressors (or both) to combine and compress multiple input signals received in one or more video signal formats into a compressed signals that can be transmitted using less bandwidth or on fewer cables than the set of original video signals.

p-0070For example, in some systems, the electrical domain signal aggregation module may implement a visually lossless (or visually lossy) compression, followed by a mathematically lossless (or mathematically lossy) compression, followed by a TDM module. The corresponding electrical domain deaggregation module would implement a TDM demultiplexing stage, followed by a mathematical decompression and then a visual decompression to recreate versions of the original signals.

p-0071Reference is next made to <figref idrefs="DRAWINGS">FIGS. 4 and 5</figref>, which illustrate another system <b>400</b>. Components of system <b>400</b> that are similar to components of systems <b>100</b> and <b>300</b> are identified by similar reference numerals. System <b>400</b> includes a plurality of input cards <b>480</b>, output cards <b>482</b> and a packet switched router <b>484</b>, in addition to components corresponding to those of systems <b>100</b> and <b>300</b>.

p-0072Each input card <b>480</b> has a plurality of input ports <b>416</b> at which a plurality of input signals <b>417</b> may be received, including electrical input signals and optical input signals. Controller <b>410</b> assigns a unique master signal code to each input signal as it is received. The unique master signal code is used to uniquely identify is signal while it is processed through various components of system <b>400</b>.

p-0073Each input card includes an electrical domain signal aggregation module <b>424</b> and an optical domain signal aggregation module <b>404</b>. Electrical domain input signals <b>417</b> are combined through electrical domain signal aggregation module <b>424</b> and optical domain signal aggregation module <b>404</b> to produce compressed optical signals <b>452</b>. Each signal <b>417</b> is tagged with its corresponding unique master signal code processed through the electrical domain signal aggregation module <b>424</b> and optical signal aggregation module <b>404</b> such that each signal <b>417</b> can be identified using its unique master signal code. Optical domain signals <b>417</b>, such as signal <b>417</b><i>o</i>, received at input ports <b>416</b>, are also tagged with their corresponding unique master signal codes and may be coupled optical domain signal aggregation module <b>404</b> which combines them into compressed optical signals <b>452</b>. The compressed optical signals <b>452</b> are coupled to a packet switched router <b>484</b>.

p-0074Packet switched router <b>484</b> includes one or more signal extraction module <b>486</b> a memory module <b>488</b> and one or more signal transmission modules <b>492</b>. Like other components of system <b>400</b>, packet switched router <b>484</b> is coupled to and operates under the control of controller <b>410</b>. Only some of the connections between the controller <b>410</b> and other components of system <b>400</b> are shown to avoid cluttering <figref idrefs="DRAWINGS">FIG. 4</figref>.

p-0075One or more compressed optical signals <b>452</b> may be coupled to each signal extraction module <b>486</b>. Compressed optical signals <b>452</b> may be received by the signal extraction module <b>486</b> from one or more input cards <b>480</b> or from an external device at an input port <b>494</b>.

p-0076Signal extraction module <b>486</b> extracts each signal <b>417</b> (or, more precisely, the version of the signal <b>417</b> that is included in the compressed optical signal <b>452</b>). Signal extraction module <b>475</b> converts each signal <b>417</b> into a corresponding electrical signal and packetizes the signal to form a packetized signal <b>488</b> comprising a series of packets <b>489</b> corresponding to each signal <b>417</b>. Referring briefly to <figref idrefs="DRAWINGS">FIG. 5</figref>, each packet <b>489</b> in each packetized signal <b>488</b> includes the unique master signal code <b>490</b> corresponding to the signal. The signal <b>417</b> is divided into portions that are encoded in each packet <b>489</b> as a data payload.

p-0077Memory module <b>488</b> may be any type of memory device that is capable of storing packets <b>489</b> generated by the signal extraction module <b>486</b>. In some embodiments, memory module <b>488</b> may be organized into a series of first in-first out (FIFO buffers) <b>490</b>. As a signal extraction model <b>486</b> generates each packet <b>489</b> in a packetized stream <b>488</b>, the packets <b>489</b> are stored sequentially in a FIFO buffer <b>490</b>.

p-0078Each signal transmission module <b>492</b> is coupled to the memory module <b>488</b> to retrieve packets <b>489</b> and one or more output ports <b>494</b>.

p-0079Each signal transmission module <b>492</b> may be configured by controller <b>410</b> to retrieve packets <b>489</b> corresponding to one or more packetized stream <b>488</b> from the corresponding one or more FIFO buffers <b>490</b>, convert the packetized streams into one or more optical signals and produce one or more compressed optical signals <b>462</b> corresponding to the one or more packetized stream. In some embodiments, the compressed optical signals <b>462</b> may be assembled with similar content and structure as described above in relation to signals <b>152</b>. Each compressed optical signal <b>462</b> is made available at an output port <b>496</b> to devices <b>470</b> coupled to system <b>400</b>. Some or all of the compressed optical signals <b>462</b> may be coupled to an output card <b>482</b> while others may be coupled to external devices <b>470</b>. The output card <b>482</b> may include an optical deaggregation module <b>406</b> and an electrical deaggregation module <b>425</b> for providing one of more output signals <b>419</b> corresponding to a packetized signal included in a compressed optical signal <b>462</b>.

p-0080Input cards <b>480</b> couple some or all of the input signals <b>417</b> to switching fabric <b>420</b>. Switching fabric <b>420</b> operates in a manner similar to switching fabric <b>110</b> as described above. Input signals <b>417</b> are thus coupled to output ports <b>418</b> as output signals <b>419</b>. Switching fabric <b>420</b> operates as a crosspoint switch that coupled an input signal <b>417</b> received at one input port <b>416</b> to one or more output signals <b>418</b>. In some embodiments, switching fabric <b>420</b> may operate in the electrical domain only to switch electrical domain input signals <b>417</b> to output terminals <b>418</b>. In other embodiments, switching fabric <b>420</b> may additional or alternatively include an optical domain switch to couple optical input signal <b>417</b> to output terminals <b>418</b>.

p-0081System <b>400</b> includes both a crosspoint switch <b>420</b> and a packet based router or switch <b>484</b>. Input signals <b>417</b> may be coupled through one or both of the crosspoint switch and the packet based router.

p-0082In some embodiments, a system may include only a packet based router and may not include a crosspoint switching fabric <b>420</b>. In such embodiments, input signals <b>417</b> are available to external devices <b>470</b> as part of a compressed optical signal <b>452</b>.

p-0083The present invention has been described here by way of example only. Various modification and variations may be made to these exemplary embodiments without departing from the spirit and scope of the invention, which is limited only by the appended claims.